My most common use case is probably looking up stuff that may or may not be in a dict.
if (val := dct.get(key)) is not None:
# do stuff with val
I guess that's pretty similar to what you were doing?
Sometimes I also use it in some crazy list comprehension thing when I get backed into a corner, though it's hard to think of an example off the top of my head? It usually happens when I'm in a rush and desperate to get something working, but it has an uncanny way of being just the thing you need at that point.